1. Field of the Invention
The present invention relates to a diaphragm damper.
Further, the present invention relates to a diaphragm damper which is used for reducing pulsation generated in a high-pressure pump used in an engine.
2. Description of the Conventional Art
There has been conventionally known a high-pressure pump which pressurizes fuel supplied from a fuel tank on the basis of a reciprocating movement of a plunger so as to pressure feed to an injector side.
In this kind of high-pressure pump, a fuel chamber is formed in a fuel inlet side, and the fuel is pressurized and discharged by repeating “suction stroke” which sucks the fuel from the fuel chamber to a pressurizing chamber when a plunger moves down, “metering stroke” which returns a part of the fuel in the pressurizing chamber to the fuel chamber when the plunger moves up, and “pressurizing stroke” which pressurizes the fuel when the plunger further moves up after a suction valve is closed.
The high-pressure pump mentioned above has a diaphragm damper for reducing the pulsation generated in the fuel chamber built-in.
Further, the high-pressure pump is variously designed to enhance an effect of reducing the pulsation in the diaphragm.
For example, Japanese Unexamined Patent Publication No. 2004-138071 discloses a device which employs an elastic member for a support member supporting a metal diaphragm constructing a diaphragm damper (Japanese Unexamined Patent Publication No. 2004-138071).
However, in the device described in Japanese Unexamined Patent Publication No. 2004-138071, since the elastic member pinches the metal diaphragm from both upper and lower side directions, a space occupied by the elastic member becomes large, thereby blocking a space in which the fuel flows within the fuel chamber.
Therefore, an amount of the fuel which can be sucked into the fuel chamber is reduced, and there is a risk that the effect of reducing the pulsation by the diaphragm can not be sufficiently obtained.
Further, parts of the high-pressure pump oscillate on the basis of an operation of a suction valve, a plunger and a discharge valve, at the driving time of the high-pressure pump.
The oscillation is transmitted to the fuel, and is transmitted as the pulsation to a piping which is connected to the high-pressure pump, and there is a problem that an abnormal noise is generated due to resonance of the oscillation.
Consequently, there has been proposed a diaphragm damper which is structured such as to support an outer peripheral portion of the metal diaphragm by a rubber-like elastic member and a wave washer (a pressing member) (Japanese Unexamined Patent Publication No. 2012-132400).
However, since the diaphragm damper is structured such as to elastically support the outer peripheral portion of the metal diaphragm by the rubber-like elastic member and the wave washer (the pressing member), a structure is complicated, and the rubber-like elastic member and the wave washer (the pressing member) has a reduced degree of freedom in shapes.
As a result, it has been hard to optionally set an amount of volume change caused by the resonance frequency and the pressure, and it has been hard to achieve optimization of a diaphragm damper performance.